The present application relates to the conversion of alkanes to unsaturated halogenated products such as vinyl halides. More particularly, it relates to the conversion of ethane directly to vinyl chloride in high yields by the oxychlorination reaction utilizing a novel highly selective catalyst.
The conversion of hydrocarbons to useful halogenated hydrocarbons by the so-called "oxychlorination" reaction, i.e., the reaction of the hydrocarbon, a hydrogen halide as the source of the halogen and a source of elemental oxygen, in the presence of copper-containing catalysts is well known in the art. It is known, for example, to react ethane with hydrogen chloride and oxygen in contact with catalysts which include copper oxides, copper chlorides, copper oxychlorides, copper silicates and the like to produce chlorinated hydrocarbons such as vinyl chloride, ethyl chloride, ethylene dichloride and the like. The yields of any desired specific chlorinated products, however, have been generally poor which has led to a search for active catalysts to give cleaner or more selective reactions. One such catalyst is described in U.S. Pat. No. 3,173,962. This patent teaches the oxychlorination of an alkane having from 2 to 6 carbon atoms and preferably ethane in the presence of an iron phosphate preferably supported on an inert carrier such as silica, for example. Other metallic cations such as nickel, cobalt, copper, chromium, tin, lead, cerium, manganese, bismuth, magnesium, cadmium, vanadium and generally metals of Groups I through IV of the Periodic Table are disclosed as useful in conjunction with iron. The products obtained with this catalyst are predominantly ethylene, ethyl chloride and sometimes 1,2-dichloroethane (DCE), also called ethylene dichloride.
In another patent, No. Br. 1,039,369, the conversion of ethane to vinyl chloride by oxychlorination in the presence of water is disclosed using as catalysts inorganic oxygen-containing compounds such as simple oxides and oxychlorides of multivalent metals such as iron, cerium, manganese, uranium, vanadium, nickel, chromium and cobalt together with promoters which are inorganic compounds of Li, Na, K, Pb, Ce, Ca, Mg, Sr, Ba, Zn, Cd, B, In, P and Tl, The catalysts can be initially introduced in the form of oxygenated compounds such as carbonates, nitrates, phosphates and hydroxides and thus it is disclosed inorganic compounds resulting from this form of introduction may also be present in the reaction zone. Even with the preferred iron-containing catalysts, and steam as a reactant, however, the selectivity of conversion of ethane to vinyl chloride in a single-step reaction does not generally average 50%.
Other catalytic compositions disclosed as useful for converting ethane directly to vinyl chloride are described in U.S. Pat. Nos. 3,420,901 and 3,557,229. In the former patent, a complex copper-alumina catalyst is employed in the oxychlorination reaction but there is no indication of the effectiveness of the catalyst for producing vinyl chloride from ethane. There are no examples directed to the use of ethane as a reactant to support the bare disclosure. In the latter patent, a catalyst melt formed from a chloride of a multivalent metal, such as copper chloride, is employed but only 37% of the ethane converted goes to the production of chlorinated hydrocarbons including vinyl chloride which constituted only 18.8% of the chlorinated products mixture.
It is evident from the foregoing consideration of the prior art, that the known processes for producing vinyl chloride from ethane in one step suffer from the obvious disadvantage that the known catalysts for the reaction are not highly selective. It is, accordingly, an object of the present invention to provide an oxychlorination process utilizing a novel catalyst to produce vinyl chloride in high yields in one step from ethane. This and other objects and advantages of the invention will become more readily apparent from the following detailed description of the invention.